This invention relates to an improved heat exchanger tube cleaning element capturing device.
It is known from the above-identified patents to connect individual elongated cleaning element capturing cages or baskets to both ends of longitudinally extending tubes disposed in a heat exchanger housing. The tube ends are held in position at both ends by transverse tube sheets. The baskets are adapted to contain shuttleable cleaning elements such as brushes. Fluid flowing in one direction through the tubes keeps the cleaning elements captured within their respective basket chambers, while the fluid discharges outwardly through openings in the basket walls. Upon reversal of fluid flow, the cleaning elements are forced out of their baskets and through the tubes to the baskets at the opposite tube ends to thereby perform a tube cleaning action.
Many baskets are designed of slightly flexible plastic and with their elongated body portions formed by alternating ribs and fluid flow-through slots which terminate in an annular outer end ring. The inner edge portion of the ring is alternately joined to the ribs or exposed to form the outer slot ends. For purposes of retaining a cleaning element within the basket and yet allowing the cleaning element to be inserted or removed for more complete access to the tube interiors, a plurality of circumferentially spaced chordally inwardly extending nib-like projections have been integrally mounted to the outer end of the basket Heretofore the projections have been disposed in a single plane. See U.S. Pat. No. 3,973,592.
Many cleaning elements have comprised elongated tube scrubbing devices, such as brushes, having conical end caps. When inserting such a cleaning element into a basket through the aforementioned projections, it has been found that at least one of the end caps had to be forced past the projections, causing the latter to bend and sometimes break off. Removal of the cleaning element from the basket has been subject to similar problems. Furthermore, in the event a projection weakens or breaks, the cleaning element may escape from the basket altogether.
It is a task of the present invention to provide a projection-type cleaning element retaining means on the outer end of the basket which is constructed to permit insertion and removal of the cleaning element without bending or breaking of the projections, and while effectively reduces the opportunity for the cleaning element to escape from the basket during outward fluid flow therethrough.
In accordance with the various aspects of the invention, the cleaning element retaining means comprises opposed longitudinally offset projections which are disposed in axially spaced planes. In the embodiment disclosed herein, each plane contains a pair of circumferentially spaced projections. The longitudinal offset is such that a space is provided through which the concial end caps of the cleaning element may be "threaded" or manipulated by tipping the cleaning element at an angle to the basket axis and then pushing or pulling the cleaning element through.
Once the cleaning element is positioned within the basket, the longitudinally innermost projections act as a stop. During fluid flow outwardly through the basket, if for any reason the innermost projections fail to function and the cleaning element starts to move axially outwardly, the longitudinally outermost projections will function as a supplemental stop.